It is known to tie off or simply knot the filling end of a balloon after the latter has been filled with air or a gas. However, in such a case it is possible only with difficulties to additionally replenish the air of a flaccid balloon or even to depressurize the balloon after use and refill the same upon reuse.
The invention is based on the object of overcoming this deficiency and furthermore of taking care to provide the balloon, if desired, additionally with internal illumination.